#include <algorithm>
#include <bitset>
#include <climits>
#include <complex>
#include <fstream>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <regex>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <thread>
#include <tuple>
#include <type_traits>
#include <vector>

#include <stdio.h>

using ll = long long;
using namespace std;
const int M = 1e9 + 7;

int main() {
    ios::sync_with_stdio(false);
    int n, s, k;
    cin >> n >> s >> k;

    int st = k * n * (n - 1) / 2;
    vector<vector<int>> dp(n + 1, vector<int>(s + 1));
    dp[0][0] = 1;

    if (st > s) {
        cout << 0 << endl;
    } else {
        s -= st;
        for (int i = 1; i <= n; i++) {
            for (int j = 0; j <= s; j++) {
                if (j - i >= 0)
                    dp[i][j] = (dp[i][j - i] + dp[i - 1][j]) % M;
                else
                    dp[i][j] = dp[i - 1][j];
            }
        }
        cout << dp[n][s] << endl;
    }

    return 0;
}